ISPS:DEFINING VARIABLES

OPERATIONALLY

KDPM & KPLI LECTURE NOTES

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INTRODUCTORY INFORMATION

• The method or procedure used to measure a variable is called an operational definition. Thus an operational definition tells what operation is performed (and observed) and how it is measured.

• If you can measure a variable directly using standard systems of measurement, you do not need to define it operationally. Eg: depth – ruler, temperature – thermometer, time – stopwatch.

• Defining operationally involves finding equivalent ways of measuring something indirectly that cannot be conveniently measured directly. Eg: pendulum activity – measure period in terms of number of swings per 15 seconds because time of one swing could not be measured conveniently.

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INTRODUCTORY INFORMATION

• Different investigators may use different operationally definition for the same variable.– Example: “investigation to test the effects of Vitamin E

on the endurance of a person”.– The variable “endurance of a person” could be defined

operationally many different ways;• The number of hours a person could stay awake.• The distance a person could run without stopping.• The number of jumping jacks a person could do

before tiring.

• Operational definition should be EXPLICIT enough that another investigator could carry out the measurement without any further information from the investigator.

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EXAMPLE 1

A study was done to determine if safety advertising had any effect on automobile accidents. Different numbers of billboards were put up in Keningau over a period of four months to see if the number of people hospitalized because of auto accidents was affected. In January, five billboards carried safety messages; in February there were ten, in March there were fifteen; and in April there were twenty.During each of these four months, a record of the number of people hospitalized because of accidents was measured.

• Identify the MV and RV.• How was each variable operationally defined?

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SAMPLE ANSWER FOR EXAMPLE 1

MANIPULATED VARIABLE

SAFETY ADVERTISING

OPERATIONAL DEFINITION

Number of safety billboards put up in the town during each month

Observed : safety billboards

Operation to measure: counting the number of billboards erected each month

RESPONDING VARIABLE

AUTOMOBILE ACCIDENTS

OPERATIONAL DEFINITION

Number of people who are hospitalized because of automobile accidents.

Observed : people who are hospitalized because of automobile accidents.

Operation to measure: counting the number of hospitalized people

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EXAMPLE 2

A study was done to determine the effect that exercise has on pulse rate. Teacher trainees rode bikes for different numbers of kilometers and then their pulse rate was measured. One group rode 10 km, a second group rode 20 km, a third group rode 30 km and a fourth group rode 40 km. Following the exercise the pulse rate was immediately measured by counting the pulse for one minute.

• Identify the MV and RV.• How was each variable operationally defined?

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SAMPLE ANSWER FOR EXAMPLE 2

MANIPULATED VARIABLE

AMOUNT OF EXERCISE

OPERATIONAL DEFINITION

Number of kilometer a person rode

Observed : distance in km

Operation to measure: counting (measuring) the number of kilometers a person rode

RESPONDING VARIABLE

PULSE RATE

OPERATIONAL DEFINITION

Number of heartbeats felt at the wrist following exercise.

Observed : heartbeats.

Operation to measure: counting number of heartbeats

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NOW IT’S YOUR TURN

• DO THE FOLLOWING EXERCISE INDIVIDUALLY.

• REMEMBER !!!! THERE ARE A VARIETY OF WAYS TO OPERATIONALLY DEFINE A VARIABLE. WRITE AT LEAST THREE.

• BE CREATIVE. I KNOW YOU CAN HONESTLY DO IT!!!

• THINK! THINK! THINK!

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EXERCISE 1

A student wants to measure the absorbency of paper towels.

How does he operationally define “absorbency of paper towel”?

1. Measure the amount of water that remains after a crumpled paper towel has been placed in 25 ml of water for 5 minutes.

2. Measure the amount of water that collects after 25 ml of water has been poured through a crumpled paper towel.

3. Measure the height that water reaches after the end of a folded paper towel has been inserted in water for 15 minutes.

Possible Operational Definitions

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EXERCISE 2

You want to operationally define the variable “size of a person”.

Write at least 3 ways this variable could be defined operationally.

1. The reading in kilograms obtained when a person steps on a scale.

2. The smallest number showing when a person stands against a ruler which extends from the floor up.

3. The amount of water that overflows when a person is submerged in a full bathtub.

4. The amount of tape required to encircle the chest, waist and hips.

Possible Operational Definitions

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EXERCISE 3

You are an expert in agriculture. You are using beans in an experiment.

Write at least 3 ways to define operationally the variable “amount of plant growth”.

1. Count the number of leaves on a plant. Wait two weeks and count them again.

2. Measure the distance from the soil to the uppermost leaf. Ten days later, measure it again.

3. Weigh the plant and its pot. Wait one month and do it again. The difference is how much it grew.

Possible Operational Definitions

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EXERCISE 4A primary school has a program for increasing student’s enjoyment of reading.

List at least 3 ways that “enjoyment of reading” could be operationally defined. Think of some specific things you could measure with your students that would indicate their enjoyment of reading.

1. Amount of time students voluntarily spend at the reading table.

2. Number of references to books read during sharing time.

3. Number of voluntary book reports.

4. Number of books taken home.

Possible Operational Definitions

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EXERCISE 5

One of the goals of SK IPKS is that all children acquire a concern for their environment.

What are some of the ways that we might operationally define this variable? Describe at least three.

1. The number of special projects students choose to do on environment matters

2. The weight of rubbish picked up on the playground each week

3. The number of paper bags thrown away (instead of reused) from the cafeteria

4. The number of paper towels used in the washrooms

5. The number of posters on environmental matters in a show-your-concern-with-a-poster contest

Possible Operational Definitions

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EXERCISE 6An investigation is underway to see how the initial temperature of a liquid affects the amount of evaporation.

Describe at least three ways that “amount of evaporation” could be operationally defined.

1. Measure the depth of the liquid. Measure it again twenty-four hours later.

2. Pour a known quantity of liquid into an open container. Measure its volume again three hours later.

3. Weigh the container of liquid. Twenty minutes later, weigh it again. The difference is the amount of evaporation.

Possible Operational Definitions

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THANK YOU

POUNSIKOU

XIE XIE

ARIGATO

DANKE

DANK U WEL

NANEDRI

GARCIAS